FNKFX vs. FZFLX

Last updated Jun 4, 2026

FNKFX (Fidelity Mid-Cap Stock K6 Fund) and FZFLX (Fidelity SAI Small-Mid Cap 500 Index Fund) are both Mid Cap Blend Equities funds from Fidelity. Over the past 5 years, FNKFX returned 11.69%/yr vs 12.03%/yr for FZFLX. With a 0.95 correlation, they move nearly in lockstep. FNKFX charges 0.52%/yr vs 0.05%/yr for FZFLX.

Performance

FNKFX vs. FZFLX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Mid-Cap Stock K6 Fund (FNKFX) and Fidelity SAI Small-Mid Cap 500 Index Fund (FZFLX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, FNKFX achieves a 17.30% return, which is significantly lower than FZFLX's 33.04% return.

FNKFX

• 1D: 1.64%
• 1M: 3.92%
• YTD: 17.30%
• 6M: 17.71%
• 1Y: 30.45%
• 3Y*: 20.76%
• 5Y*: 11.69%
• 10Y*: —

FZFLX

• 1D: 1.53%
• 1M: 6.05%
• YTD: 33.04%
• 6M: 33.74%
• 1Y: 48.52%
• 3Y*: 24.40%
• 5Y*: 12.03%
• 10Y*: 14.07%

*Multi-year figures are annualized to reflect compound growth (CAGR)

FNKFX vs. FZFLX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019
FNKFX Fidelity Mid-Cap Stock K6 Fund	17.30%	11.07%	21.99%	11.55%	-5.98%	27.16%	11.27%	8.97%
FZFLX Fidelity SAI Small-Mid Cap 500 Index Fund	33.04%	10.76%	15.52%	17.75%	-15.62%	20.40%	19.78%	8.77%

Correlation

The correlation between FNKFX and FZFLX is 0.94, indicating a strong positive relationship between their price movements. Combining them offers limited diversification - they tend to fall together during downturns.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.94
Correlation (3Y) Calculated over the trailing 3-year period	0.96
Correlation (5Y) Calculated over the trailing 5-year period	0.96
Correlation (All Time) Calculated using the full available price history since Jun 14, 2019	0.95

The correlation between FNKFX and FZFLX has been stable across timeframes, ranging from 0.94 to 0.96 - a consistent structural relationship.

Return for Risk

FNKFX vs. FZFLX — Risk / Return Rank

Compare risk-adjusted metric ranks to identify better-performing investments over the past 12 months.

FNKFX

FNKFX Risk / Return Rank: 58
FNKFX Sharpe Ratio Rank: 47
FNKFX Sortino Ratio Rank: 46
FNKFX Omega Ratio Rank: 43
FNKFX Calmar Ratio Rank: 80
FNKFX Martin Ratio Rank: 75

FZFLX

FZFLX Risk / Return Rank: 74
FZFLX Sharpe Ratio Rank: 71
FZFLX Sortino Ratio Rank: 58
FZFLX Omega Ratio Rank: 58
FZFLX Calmar Ratio Rank: 91
FZFLX Martin Ratio Rank: 93

The rank (0–100) shows how this investment's returns compare to the risk taken. Higher = better. Based on the past 12 months of data, combining Sharpe, Sortino, and other metrics used by quantitative funds and institutional investors.

FNKFX vs. FZFLX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Mid-Cap Stock K6 Fund (FNKFX) and Fidelity SAI Small-Mid Cap 500 Index Fund (FZFLX). Risk-adjusted metrics are performance indicators that assess an investment's returns in relation to its risk, enabling a more accurate comparison of different investment options.

	FNKFX	FZFLX	Difference
Sharpe ratio: Return per unit of total volatility	2.02	2.44	-0.43
Sortino ratio: Return per unit of downside risk	2.85	3.22	-0.37
Omega ratio: Gain probability vs. loss probability	1.35	1.42	-0.07
Calmar ratio: Return relative to maximum drawdown	3.69	4.77	-1.08
Martin ratio: Return relative to average drawdown	14.28	20.14	-5.86
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FNKFX vs. FZFLX - Sharpe Ratio Comparison

The current FNKFX Sharpe Ratio is 2.02, which is comparable to the FZFLX Sharpe Ratio of 2.44. The chart below compares the historical Sharpe Ratios of FNKFX and FZFLX, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Sharpe Ratios by Period

	FNKFX	FZFLX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.02	2.44	-0.43
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.62	0.57	+0.05
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	0.67	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.66	0.63	+0.03

Drawdowns

FNKFX vs. FZFLX - Drawdown Comparison

The maximum FNKFX drawdown since its inception was -41.25%, roughly equal to the maximum FZFLX drawdown of -42.03%. Use the drawdown chart below to compare losses from any high point for FNKFX and FZFLX.

Drawdown Indicators

	FNKFX	FZFLX	Difference
Max Drawdown Largest peak-to-trough decline	-41.25%	-42.03%	+0.78%
Max Drawdown (1Y) Largest decline over 1 year	-8.67%	-10.68%	+2.01%
Max Drawdown (3Y) Largest decline over 3 years	-21.86%	-22.29%	+0.43%
Max Drawdown (5Y) Largest decline over 5 years	-21.86%	-24.77%	+2.91%
Max Drawdown (10Y) Largest decline over 10 years	—	-42.03%	—
Current Drawdown Current decline from peak	0.00%	-0.33%	+0.33%
Average Drawdown Average peak-to-trough decline	-4.98%	-5.74%	+0.76%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.23%	2.52%	-0.29%

Volatility

FNKFX vs. FZFLX - Volatility Comparison

The current volatility for Fidelity Mid-Cap Stock K6 Fund (FNKFX) is 5.13%, while Fidelity SAI Small-Mid Cap 500 Index Fund (FZFLX) has a volatility of 7.41%. This indicates that FNKFX experiences smaller price fluctuations and is considered to be less risky than FZFLX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FNKFX	FZFLX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.13%	7.41%	-2.28%
Volatility (6M) Calculated over the trailing 6-month period	12.49%	17.71%	-5.22%
Volatility (1Y) Calculated over the trailing 1-year period	15.87%	20.84%	-4.97%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	18.86%	21.11%	-2.25%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	21.97%	21.11%	+0.86%

FNKFX vs. FZFLX - Expense Ratio Comparison

FNKFX has a 0.52% expense ratio, which is higher than FZFLX's 0.05% expense ratio.

Dividends

FNKFX vs. FZFLX - Dividend Comparison

FNKFX's dividend yield for the trailing twelve months is around 0.50%, less than FZFLX's 43.42% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FNKFX Fidelity Mid-Cap Stock K6 Fund	0.50%	0.59%	12.35%	0.99%	2.91%	4.03%	1.45%	0.52%	0.00%	0.00%	0.00%	0.00%
FZFLX Fidelity SAI Small-Mid Cap 500 Index Fund	43.42%	57.77%	10.20%	2.35%	79.79%	50.77%	7.19%	6.49%	7.69%	1.68%	0.93%	0.67%

Frequently Asked Questions

Can I hold both FNKFX and FZFLX in my portfolio?

With a correlation of 0.94, FNKFX and FZFLX move almost identically. Holding both adds very little diversification - you're essentially doubling your position in the same market segment. Choosing one is usually more capital-efficient.

Which is riskier, FNKFX or FZFLX?

FZFLX has higher volatility (7.41%) compared to FNKFX (5.13%). In terms of maximum drawdown, FNKFX dropped -41.25% vs FZFLX's -42.03%.

Which has better risk-adjusted returns?

FZFLX currently has the higher Sharpe Ratio (2.44 vs 2.02), meaning it's delivered slightly more return per unit of risk over the trailing 12 months. However, this ranking shifts over time - use the Risk/Return Score above for a more comprehensive view that combines Sharpe, Sortino, and other measures used by quantitative funds.